Wander to the back of the queue with a growl (3)

I believe the answer is:
err
'wander' is the definition.
(to err is to go astray)
'the back of the queue with a growl' is the wordplay.
'the back of the' says to take the final letters.
'with' says to put letters next to each other.
'a growl' becomes 'rr' (I can't justify this - if you can you should believe this answer much more).
The final letter of 'queue' is 'e'.
'e'+'rr'='ERR'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for err that I've seen before include "Drop a clanger" , "Be inaccurate" , "Make mistakes" , "Transgress" , "Boob" .)
